Dental caries is a state of a dental carious cavity caused by the dissolution of calcium from teeth and which can not naturally return to a healthy state. But, there is a state referred to as a sub-surface lesion which can return to the healthy state, in the course of the development of the dental carious cavity (“Zusetsu Ushoku-gaku” edited by Shoichi, Suga, 1990, 139). Therefore, in order to decrease dental caries, it is desirable to enhance the remineralization so that the teeth can return to the healthy state within a term during which the teeth return to the original state.
As a method for enhancing the remineralization, the use of fluorine compounds has been known for a long time. However, because the ingestion of a large amount of fluorine exhibits the toxicity, it is desired that fluorine be effectively utilized in an as smaller as possible amount. To accomplish this, the use of a substance that enhances the remineralization effect of fluorine is exemplified. For example, there is proposed a combination of fluorine and hydroxy-apatite in JP-A-1-110608. However, its effect is insufficient and is not satisfactory.
On the other hand, a zinc compound that has been utilized in the oral composition generally has an astringent or salty taste and, therefore, there is a problem that it has the very bad feeling for use upon its use.
One object of the present invention is to provide an oral composition which has the high safety and can enhance the remineralization. Another object of the present invention is to provide an oral composition which exhibits the sufficient remineralization effect and has the better feeling for use.